Many surgical systems require instruments and devices that provide for the use of fluids to irrigate surgical sites, and further provide for the aspiration of the fluids from the surgical sites, typically on a continuous or selectively intermittent process during the surgery. In many such prior systems, surgical cassettes are used to collect fluid aspirated from the surgical sites, whereby after use, due to contamination from the fluids, the now contaminated cassettes are typically disposed of. Many of the known cassettes are very expensive, and represent increased surgical costs for hospitals, and other health providers that must use such cassettes. There has been a long felt need in the art to provide devices or mechanisms for preventing the contamination of expensive surgical cassettes, thereby permitting continuous use of the primary cassette during multiple surgeries, to offer substantial cost savings to the health providers.
A vitrectomy is an example of a common surgical procedure performed for retinal eye disorders that typically requires use of the aforesaid surgical systems. More specifically, a vitrectomy is performed to remove vitreous humor (jelly-like liquid) from the posterior segment or back of eye. To maintain the integrity of the eye while vitreous is being aspirated, balanced salt solution is continually infused into the surgical site.
To perform a vitrectomy, the retinal surgeon uses one type of the aforesaid surgical systems known as a vitrectomy “unit.” The vitrectomy unit serves as a “source pump” and/or “vacuum pump”. Disposable components and instruments such as a Vitreous Cutter (cutter), Tubing Sets (tubing) and Cassette Reservoir (cassette) are attached to the vitrectomy unit. Together, the vitrectomy unit and disposable components make up a vitrectomy “system.”
The vitrectomy unit itself is usually a large stand alone device that is not sterile, and is activated by the surgeon using a foot pedal. The disposable vitreous cutter is physically held by the surgeon and placed into the eye. When the vitrectomy unit is activated, vitreous and other bodily fluids are aspirated through the cutter and tubing, and ultimately are collected within the cassette.
The cassette is usually not handled by the surgeon during the operation. Rather, a circulating nurse preoperatively secures the cassette to the vitrectomy unit. The cassette has three primary functions. First, relative to one example in the prior art, because of its special proprietary design, it allows the vitrectomy unit to activate.
In most vitrectomy units, a cassette is required for activation. The cassette is generally produced as a disposable component. Prior to the start of each vitrectomy, a new cassette is opened and installed in the vitrectomy unit. A new cassette is used because in each case the previously used cassette is contaminated from eye fluids. After the vitrectomy, the cassette is then thrown away per hospital protocol regarding bio-contamination.
Second, once the vitrectomy unit is activated by inserting the proprietary cassette, the surgeon is then permitted to control vacuum and/or aspiration flow rate via use of a foot pedal. Fluids may now be vacuumed and or/aspirated out of the eye via the cutter and carried away through the tubing for deposit into the cassette. Typical cassette designs include features that maintain a constant fluidic resistance, to assist the physician in maintaining control of the aspiration flow rates through the cutter.
Third, in addition to the first and second functions, the cassette is specially designed with proprietary features to ONLY activate a proprietary vitrectomy unit for which it was designed. Therefore, use of a certain vitrectomy unit is dependent upon using the same company's proprietary cassette. This is how companies generate residual sales after selling a one time purchase of the vitrectomy unit.
An example of one such prior surgical cassette of a vitrectomy system is disclosed in Jung et al. U.S. Pat. No. 6,059,544, entitled “Identification System For A Surgical Cassette,” issued on May 9, 2000. As shown in FIGS. 1 and 2 hereof, the cassette 10 includes a single piece plastic housing 12 that has a handle 44 for installing and removing the cassette 10 from a vitrectomy unit (not shown). The cassette 10 is a relatively complicated device, as described in the aforesaid patent. Certain, but not all of the features of cassette 10 will now be described. A cassette identification system 34 consists of a plurality of tabs 36 for identifying the cassette when it is plugged into an associated vitrectomy unit. With further reference to FIGS. 1 and 2, cassette 10 further includes aspiration lines 18 and 20, a peristaltic pump tube 16 having one end connected to an output port 30. A drain bag 14 is provided, and includes holes 32 to allow it to hang from hooks 26 provided on the cassette 10. A port 28 of the drain bag 14 is secured to an output port 30 associated with peristaltic pump tube 16. The drain bag 14 further includes a one-way valve 22 for preventing the backup of fluid into the cassette 10, and a sampling port 24 for permitting a sample of fluid to be drawn from the bag for testing, or other purposes. The cassette 10 further includes a first vacuum port 13, and a second vacuum port 15, as shown. Aspirator line 18 is connected between port 13 and a vacuum port 66. Aspirator line 20 is connected between port 15 and another vacuum port 68. Note both the cassette 10, and its associated drain bag 14, are provided by Alcon Laboratories, Inc., of Fort Worth, Tex. Due to the obvious complexity of the cassette 10, it represents a relatively high cost component for users, that must be disposed of after a first use, along with the associated drain bag or bags 14. Note that chamber 64 provides for receiving materials or aspirated liquid (contaminated eye fluid) drawn into chamber 64 through aspiration lines 18 and 20 by a vacuum produced in chamber 64 via vacuum input port 21 being connected to a vacuum source of the associated vitrectomy unit.
Alcon Laboratories, Inc. provides the cassette 10 in what they identify as a Total Plus Pack. The latter includes the cassette 10 along with a number of other disposable components.
The present inventors recognized that if a system is developed for permitting users of the aforesaid cassette 10, modified for use in the present system, to continually use the cassette, considerable cost savings will be provided. Accordingly, as described in detail below, the present inventors developed a system including a disposable surgical cassette that is substantially inexpensive relative to the cost of surgical cassettes such as the modified Cassette 10, whereby the present inventive surgical cassette is disposable, while permitting extended continuous use of the modified cassette 10 when used in association therewith. However, the present invention is not limited to permitting continual use of the aforesaid modified Alcon cassette 10, and can be used in other aspirating systems. For example, it is expected that the present inventive cassette will also have use in surgical aspirating systems in both posterior and anterior surgical fields. In addition, it is expected that the present inventive cassette will have use in industrial systems.